1. Field
The present disclosure relates generally to communication systems, and more particularly, to methods and apparatuses for packet detection.
2. Introduction
Wireless networks are widely deployed to provide various services to consumers, such as telephony, data, video, audio, messaging, broadcasts, and the like. Today, wireless networks enable broadband communications over broad geographic regions (e.g., metropolitan, regional, nationwide, or even global), as well as more localized and personalized regions. Wireless networks covering local regions have become increasing pervasive in recent years. These wireless networks are often referred to as Wireless Local Area Networks (WLANs) which have been standardized, by way of example, by the Institute of Electrical Engineers (IEEE) 802.11 committee. WLANs are deployed to cover small areas with a geographic coverage ranging from a few tens of meters to a few hundred meters. A WLAN uses unlicensed spectrum to provide access to a network, typically covering only the network operator's own property. By way of example, many homes, office buildings, campuses, hotels, transportation hubs (e.g., airports, train stations, etc.) and other facilities contain WLAN access points to the Internet.
With any wireless network, a wireless receiver must be able to detect the transmission of data packets from a wireless transmitter in the presence of noise, interference and other disturbances in the wireless channel. In IEEE 802.11 compliant networks, for example, this may be achieved by detecting at the receiver a repeating pattern in the preamble of the data packet. Typically, this is achieved by means of an autocorrelation process. However, the standard autocorrelator has the disadvantage that it triggers on any type of periodic waveform, such as, by way of example, a single tone interferer within the bandwidth of interest. Even if the interferer power is relatively low, the effect of the Automatic Gain Control (AGC) in addition to the Signal-to-Noise Ratio (SNR) gain in the autocorrelator can lead to a significant number of false alarms. This can have several detrimental effects such as flooding the receiver with false detects, which may cause an increase in packet loss. The receiver may also experience an increase in its buffer requirements to account for the large number of false alarms, as well as an increase in power consumption to process false detected packets down the receiver chain.
Accordingly, systems and methods for packet detection in wireless networks are needed.